PARKLAND, Fla. — The suspect in one of the deadliest school shootings in modern American history confessed to the police that he “began shooting students that he saw in the hallways and on school grounds,” according to a police arrest report released Thursday.

The suspect, Nikolas Cruz, 19, carried a black duffel bag and backpack, where he hid loaded magazines, the report said. He arrived at Marjory Stoneman Douglas High School in Parkland in an Uber at 2:19 p.m. on Wednesday and pulled out a semiautomatic AR-15 rifle, according to details described by the authorities at a news conference on Thursday.

Mr. Cruz also shot people inside five classrooms on the first and second floors of the freshman building. He eventually discarded the rifle, a vest and ammunition in a stairwell, blended in with fleeing students and got away, the authorities said.

After leaving the school, Mr. Cruz walked to a Walmart, and bought a drink at a Subway. He also stopped at a McDonald’s. He was arrested by the police without incident as he walked down a residential street at 3:41 p.m.

“He looked like a typical high school student, and for a quick moment I thought, could this be the person who I need to stop?” said Officer Michael Leonard.

Here are the takeaways:

• Mr. Cruz faces 17 counts of premeditated murder — one for each of the people he is accused of killing on Wednesday in a shooting that was captured on cellphone video by terrified students. He is being held without bond at the main Broward County jail, where he has been placed on suicide watch, according to Gordon Weekes, the county’s chief assistant public defender.

• The AR-15 rifle used in the attack was purchased legally, at Sunrise Tactical Supply in Florida, according to a federal law enforcement official. The arrest report said Mr. Cruz purchased it in February 2017. “No laws were violated in the procurement of this weapon,” said Peter J. Forcelli, the special agent in charge for the Bureau of Alcohol, Tobacco, Firearms and Explosives in Miami.

• The F.B.I. said on Thursday it received information last year about a comment made on a YouTube channel which has been attributed to the gunman, but was unable to identify the person.

• In Florida, an AR-15 is easier to buy than a handgun. Read more on how the AR-15 became one of the weapons of choice for mass killers, and the research that tries to explain the high rate of mass shootings in the United States.

• With this shooting, three of the 10 deadliest mass shootings in modern United States history have come in the last five months. Here is a graphic that records the grim toll of school shootings across the nation.

• A huge crowd gathered at Pine Trails Park in Parkland for an emotional vigil to commemorate the victims, 14 of whom were students. Read more about the victims here. The football team gathered separately nearby, forming a circle and locking hands before praying for a coach and an athletic director who were killed.

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Florida Shooting Suspect Appears Before Judge

Nikolas Cruz, shown with a public defender, was ordered to be held in jail without bond.

The mass shooting at Marjory Stoneman Douglas High School in Parkland, Fla., was one of the deadliest in American history.Credit
Saul Martinez for The New York Times

The victims — 14 students and three faculty — ranged from 14 years old to 49.

Among them was a popular football coach and a geography teacher credited with saving a boy’s life when he stood in front of a classroom door.

The coach, Aaron Feis, was seen as someone who looked out for students who got in trouble, those who were struggling, those without fathers at home. “He’d go out of his way to help anybody,” said Mr. Feis’s grandfather, Raymond. Read more about the victims here.

Mr. Cruz made his first court appearance, clad in an orange jail jumpsuit.

Shackled around his hands, feet and waist, Mr. Cruz was asked if he understood the circumstances. “Yes, ma’am,” he whispered.

“He’s sad. He’s mournful,” his public defender, Melisa McNeill, said afterward. “He is fully aware of what is going on, and he’s just a broken human being.”

Mr. Weekes, the chief assistant public defender, said the lawyers were still trying to piece together the details of Mr. Cruz’s life. Mr. Cruz has a “significant” history of mental illness, according to Mr. Weekes, and is possibly autistic or has a learning disability.

Photo

Nikolas Cruz.Credit
Broward County Jail

But Mr. Weekes was not yet ready to say whether he would pursue a mental health defense.

Howard Finkelstein, the chief public defender in Broward County, said the case will present a difficult question: Should society execute mentally ill people?

“There’s no question of whether he will be convicted of capital murder 17 times,” he said. “When we let one of our children fall off grid, when they are screaming for help in every way, do we have the right to kill them when we could have stopped it?”

Since his mother’s death last year, Mr. Cruz was living with another family, said their attorney.

The family that took him in, the Sneads, had seen signs of depression in Mr. Cruz, but nothing indicated that he was capable of this kind of violence, Jim Lewis, the family’s attorney, said. The family had allowed Mr. Cruz to bring his gun with him to their house, insisting that he keep it in a lockbox.

Mr. Lewis had encouraged Mr. Cruz to attend adult education courses, work toward his G.E.D., and take a job at a local Dollar Tree store, he said in a brief interview. The Sneads’ son, a junior, knew Mr. Cruz from Stoneman Douglas High.

On Wednesday, Mr. Cruz and the Sneads’ son were texting until 2:18 p.m., Mr. Lewis said — about five minutes before the first 911 calls about the shooting. “But there was nothing crazy in the texts,” Mr. Lewis said. Here is our profile on Mr. Cruz.

Gino Santorio, executive vice president and chief operating officer of Broward Health, said the hospital where Mr. Cruz was taken, Broward Health North, enacted safety protocols when he arrived on Wednesday.

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President Trump addressing the nation on Thursday.Credit
Tom Brenner/The New York Times

The staff treated the suspect “like every patient they treat,” Mr. Santorio said.

“We were able to seclude the patient, treat and get them out without any issues,” he added.

Broward Health North received nine patients, including the suspect, according to Kelly Keys, manager of emergency preparedness for the health system. Two patients died, three remain at the hospital, and three have gone home.

Video

They Survived the School Shooting. Now They Want Action.

Just hours after 17 people were killed in a mass shooting at their high school in Parkland, Fla., students turned to social media to advocate for more gun control.

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“If we’re constantly having our children worried about getting shot at, what are we telling our future?” said David Hogg, 17, a senior, who said two of his 14-year-old sister’s friends were killed. “And that’s what these people are killing, our future.”

Superintendent Runcie did not mince words: “Now is the time for the country to have a real conversation on sensible gun controls in this country,” he said.

Democrats in Congress welcomed a gun control debate. “At some point, we’ve got to say enough is enough,” Senator Bill Nelson of Florida said on the Senate floor.

But in an interview on WIBC radio on Thursday, House Speaker Paul Ryan said that public policymakers “shouldn’t just knee-jerk before we even have all the facts and the data.” He added, “We need to think less about taking sides and fighting each other politically, and just pulling together.”

In an address to the nation, President Trump announced he would visit Parkland and work with the nation’s governors “to help secure our schools, and tackle the difficult issue of mental health.” But he made no mention of guns.

The F.B.I. had information about a suspicious comment on YouTube.

Ben Bennight, a bail bondsman in Mississippi, said in an interview that he reported a suspicious comment left on his YouTube channel last fall by a user named “nikolas cruz.”

“I’m going to be a professional school shooter,” the Sept. 24 comment said.

Mr. Bennight took a screenshot of the comment and flagged it to YouTube, which removed the post. Mr. Bennight said he then left a voice mail message at his local F.B.I. field office alerting it to the comment.

Mr. Bennight, 36, said that when he originally reported the comments to the F.B.I., a pair of agents interviewed him the next morning. Mr. Bennight said two F.B.I. agents visited him a few hours after the shooting on Wednesday, spending about 15 to 20 minutes with him. The agents told him they thought the person who posted on his channel might be connected to the Florida shooting because they had the same name.

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‘We Are Broken’: Families Gather at Florida Shooting Vigil

At a candlelight vigil Thursday night for the 17 people killed in a Florida school shooting, attendees chanted, “No more guns.”

By THE NEW YORK TIMES on Publish Date February 16, 2018.
Photo by Saul Martinez for The New York Times.
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The F.B.I. on Thursday released a statement that said it received information about a comment made on a YouTube channel in September 2017. “No other information was included in the comment which would indicate a particular time, location, or the true identity of the person who posted the comment,” the statement said. The F.B.I. said it conducted database reviews and other checks, but was unable to further identify the person who posted the comment.

On Thursday, Jordan Jereb, a leader of a white supremacist group based in North Florida, told The Associated Press that Mr. Cruz had joined the group, but later Mr. Jereb said that he did not know whether that was true. Sheriff Israel said he could not confirm any ties Mr. Cruz might have had to white nationalists.

Two Instagram accounts that classmates said belonged to Mr. Cruz were filled with images of weaponry, as well as the hats and bandannas he liked to wear to school. Among more innocuous pictures of animals, including a dog and a gecko, was a picture of a slaughtered toad. In response to a comment on that image, Mr. Cruz wrote that toads tended to run away when they saw him, because “I killed a lot of them.”

Other posts on the first account, like one captioned “arsenal,” showcased collections of firearms, including what appears to be a Savage Axis bolt-action rifle, a Smith and Wesson M&P15-series rifle, and at least two shotguns.

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It was unclear whether the profile picture for that account, a face nearly entirely covered with a “Make America Great Again” hat and large bandanna, was an image of Mr. Cruz.

The profile picture for the second account also featured a face almost fully covered, this time with an Army beanie. The account included several pictures of a figure wearing several different Army hats and carrying guns and knives. It also contained a picture of a Google search for the Arabic phrase “Allahu akbar” — God is great.

Instagram did not immediately reply to a request for comment.

‘The shots were something I’ll never forget’

Moises Lobaton, a senior, was in psychology class when gunfire boomed. The students scurried to try to hide as far away from the door as possible.

“There wasn’t enough space behind the desk, so not all of the kids could fit,” he said.

Shots shattered a glass window on the door, injuring at least three of his classmates, including a girl who “wasn’t moving at all.”

“She was next to a pool of blood, but I couldn’t tell if it was hers or the guy next to hers,” he said. The boy had been shot in the arm and was bleeding profusely. His classmates wrapped the arm in cloth. Another boy called 911.

“The shots were something I’ll never forget. It sounded like bombs going off, one at a time,” he said. “If I was one or two feet to the right, I would have died.”

In New York, two students were arrested after threatening on social media to ‘gun down’ their Brooklyn high school, police said.

Cole Carlberg, 16, turned himself in, and the police picked up Joshua Schechter, 16, after receiving a 911 call at about 9 a.m. on Thursday. Both were charged with making terroristic threats, aggravated harassment and criminal possession of a weapon, a New York police sergeant, Brendan Ryan, said.

On Wednesday, the teenagers had posted on Snapchat that they had planned to shoot up Brooklyn Prospect Charter School on Fort Hamilton Parkway, Sergeant Ryan said, adding that the school contacted parents about the threat. One of the teenagers had an “air pistol rifle” that Sergeant Ryan described as a pellet or BB gun, but said it was unclear who owned it. “That’s still under investigation,” he said.